One winter morning about two years ago, marine mammal scientist Anton van Helden was driving hell-for-leather up to the far north of New Zealand. A thirteen-and-a-half hour haul would take him to the beach where the first pygmy killer whale to strand itself in New Zealand was lying, and he wasn’t going to miss the chance to collect the skeleton and perhaps tissue samples for the Museum of New Zealand, where he worked. Partway through the drive, he got a call.

Two beaked whales had been found dead at a place called Opape Beach. “They sounded for all the world like Gray’s beaked whales,” he recalls, a species that washes up relatively frequently on New Zealand’s shores, which sometimes see several hundred whale beachings per year thanks in part to the nation’s long coastline. “Maybe you can bury them,” he said to the conservation department employee at the other end of the line, “and we’ll have a look later, just to be sure.”

Van Helden gave the matter little thought until a few months had passed and his phone rang one morning before he had even gotten out of bed. It was Rochelle Constantine, a marine biologist at the University of Auckland, and her graduate student Kirsten Thompson, who had conducted routine DNA analyses on the beached whales. “I hope you’re sitting down,” Constantine said. Those animals stranded in December were not Gray’s. They were instead a pair of spade-toothed beaked whales. It was a name to make a certain kind of scientist weak in the knees: the most elusive species of whale in the world, known only from several bone fragments washed up over the course of 140 years. It had never been seen in the flesh before. Van Helden looked up at the ceiling and swore.

There are a lot of reasons to care about seeing the remains of so elusive a species — beyond simply the thrill of the chase and the brass-ring quality of an actual discovery. Humans have made a hash of the oceans — depleting fish stocks, slaughtering dolphins and whales, pouring pollutants into coastal waters. Part of the reason we are so cavalier is that so much of the ocean is invisible to us on a day-to-day basis; if you don’t know what’s there, you don’t know what you’re destroying. The spade-toothed beak whale, which was written up in the new issue of Current Biology, is a lesson both in the diversity of the fragile oceans and the painstaking sleuthing that is required to study it.

After van Helden received his early-morning call, he and his colleagues got to work. They gathered all the information they could about the beached pair, including measurements and a set of photographs taken at the scene of the beaching. They worked with the Whakatohea Iwi, the Maori tribe in the area where the whales had been found, and the New Zealand Department of Conservation, to get the skeletons exhumed, and Van Helden produced a detailed anatomical illustration of the animal, which also appears in Current Biology.

The pair on the beach were an adult female, measuring just over 17 ft. (5.3 m), and a juvenile male, 11.5 ft. (3.5 m) from beak to tail fin. They lack the species’ signature protruding teeth, which occur only in adult males. The shape and coloration of both specimens are subtly different from other beaked whales — subtle enough, in fact, that they would be easy to confuse with the more commonly seen Gray’s.

What allowed the team to make a firm identification was the genetic information collected from the three bones that until now have been our only evidence of the spade-toothed’s existence. The first sign of the animal was a lower jaw found on New Zealand’s Chatham Islands in 1872, bearing two jutting, triangular teeth. Later on, two skulls without lower jaws, one found in 1950 in New Zealand, the other found all the way across the Pacific on Robinson Crusoe Island in 1986, were proven by DNA analysis to be from the same distinct species. But while scientists made educated guesses about what an intact spade-toothed would look like, extrapolating from its relatives could take them only so far. That’s why this find had the team so excited. “It was the first time ever that anybody had ever had even a hint of what these things looked like,” van Helden says.

The new discovery is a big step forward for scientists interested in beaked whales, but there is still much to learn about both this species and its close relatives. Thompson is working on a project that uses genetic information from beached beaked whales to glean insight into the elusive creatures’ familial relationships. And seeing the animal alive in the wild remains a tantalizing goal of many scientists. Scott Baker, a marine biologist at Oregon State University and a co-author of the paper who has studied whales and dolphins for 30 years, saw his first live, open-ocean beaked whale just last month, in Samoa. The sighting lasted about 4 seconds before the animal dove — too brief to tell if it was a spade-toothed. “Their environment is very remote,” he says. “It’s deep water, and they’re submerged for maybe 96% of their lives.”

It’s one of the sad ironies of the marine biologist’s work that the only way to get a more lingering look at animals like these is when they wash up on beaches — like ornithologists studying birds that are invisible until they slam into a window. “Here we have an animal which is over 5 meters long, the size of a big car, that has to come to the surface to breathe, and yet no one has ever seen one alive,” says van Helden. “It typifies how little we know about the ocean.” The new find sheds at least a tiny bit of light on that often dark world, reminding us of an environment we have the power to destroy — and the responsibility to preserve.